This invention relates to an optical disc on which video data, audio data, and the like are recorded, an optical disc recording apparatus for recording data onto the optical disc, and an optical disc reproducing apparatus for reproducing the data recorded on the optical disc.
In recent years, moving-picture-compatible optical disc playback systems have been developed which play back an optical disc on which video data, audio data, and the like have been recorded. They have been widely used in the form of, for example, LDs (Laser Discs) or video CDs for the purpose of reproducing movie software or karaoke.
In this connection, the DVD (Digital versatile Disc) standard employing the internationally standardized MPEG-2 (Motion Picture Experts Group 2) scheme and the AC (Audio Compression)-3 scheme has been proposed.
The DVD standard supports MPEG-2 for moving picture compression scheme and AC-3 audio and MPEG audio for audio recording scheme according to the MPEG-2 system layer architecture. The DVD standard further supports sub-picture data, obtained by run-length compressing the bit map data for subtitles, and special playback control data (navigation pack) such as fast-forward playback or fast-rewind playback data.
Furthermore, the DVD standard supports ISO 9660 and micro UDF (or UDF Bridge) to allow computers to read data of DVD.
Presently, however, the DVD standard takes no account of home recording/reproducing systems. When home recording/reproducing systems are constructed according to the standard, the following problem arise.
In DVD, information on title is defined as text information.
The text information, which is used for retrieval or search, has not been used much, because the DVD-ROM video has a menu (menu pictures) the title producer created, such as VMGM (video manager menu) or VTSM (video title set menu). In home recording/reproducing systems, however, a menu cannot be entered beforehand to record TV programs or moving pictures and still pictures (photographic data) from a camera into a DVD-RAM. Thus, retrieval or search using the text information becomes important.
In the DVD-ROM video, however, the text information has been created, taking no account of language. More specifically, in European countries and Asian countries, language differs from one TV station to another or from one program to another.
Additionally, assume a case where a person goes abroad, carrying a DVD recorder with him or her, and does video-recording where he or she is staying. Under this assumption, if it is unknown which language the text information was recorded, the DVD recorder (or player) cannot judge whether or not a character generator (e.g., kanji ROM) corresponding to its language code is provided therein, when the text information is decoded. This makes the decoding difficult. Moreover, when the text information does not correspond to the language, information retrieval (search) and the like cannot be performed at all.